A lawsuit filed by the city of Los Angeles against construction firms that built a Los Angeles International Airport runway five years ago could hinge on how much airport officials knew about alleged defects and when they knew it, say attorneys not involved in the case.

The key issue may come down to timing, lawyers say. Los Angeles generally has four years from the time it discovered problems with Runway 25L to file a lawsuit. But the clock doesn’t necessarily start ticking when the project is finished: If the city did not discover the purported runway issues immediately, it could have as long as 10 years to file suit.

Lawyers for a construction joint venture named in the suit — Tutor-Saliba/O&G Industries — argued last month in court papers that, by waiting until nearly five years after the runway’s completion, the city missed its deadline for filing. But like many legal issues, it’s not that simple.

“There is a four-year statute of limitations for dealing with construction projects, but that’s for what they called patent defects — in other words defects that would be apparent or visible,” said Robert Span, an attorney who specializes in aviation matters at Steinbrecher & Span LLP in Los Angeles.

“There’s a 10-year statute of limitations for construction projects where the defect that is alleged is what’s called latent — something that would not be readily apparent.”

In the complaint filed in October in Los Angeles Superior Court, city attorneys argued that the concrete used on the job did not conform to agreed-upon project requirements. The city said the runway was wearing out prematurely. Since then, airport officials have declined to comment, saying they do not speak about pending litigation. They have said that the runway remains, for now, safe for airport operations.

The case is relatively straightforward construction litigation, attorneys say. Entities like Tutor-Saliba often argue that the plaintiff should have realized the runway was defective immediately. In court papers, Tutor-Saliba has not admitted the runway is faulty — only that, if it is, the airport should have realized the problems while it was being built. Tutor-Saliba attorneys argue that airport officials were aggressively monitoring all facets of construction and should have known of potential problems years before the lawsuit was filed.

“It’s a common defense,” said Tim Pierce, an attorney who specializes in construction issues at K&L Gates LLP in Los Angeles. “It is certainly raised in most cases and only works in some.”

There could be considerable discussion about when the city learned of the cracks, Pierce said.

“In this particular case, if the cracking was unknown at the time, then it would be latent defect, and you would be applying the 10-year statute,” Pierce said.

He said entities like Los Angeles sometimes try to file suits within four years, if only to avoid arguments on what was patent and what was latent.

“If there’s some pretty strong evidence that you have known all along, that would be a prudent thing to do,” Pierce said. “Sometimes you file it in four years just to avoid the issue. But that doesn’t mean that not filing earlier was the wrong thing.”

It is not, however, clear whether this issue will ever be decided by a judge. Attorneys say the majority of cases like these tend to be settled before trial.